well if you flashed the 1.44 hboot your pc must work in fastboot
what state is the phone in when you run the RUU ? bootloader / recovery / Android OS ?
The bootloader is 1.44 now, recovery is stock recovery from the GPE edition. Strangely it still boots up to android 4.4.2 Kitkat GPE edition.
I make sure it's in fastboot state and run the RUU, I'm going to try another RUU in a few seconds.